In the production of adjustable type hose clamps which are commonly used on resilient tubes or hoses in appliances such as clothes washing and dishwashing machines and in connection with engines for motor vehicles, there have been many different forms of hose clamps either proposed or used for securing a hose to a tubular fitting. One of the most common types of hose clamps incorporates a cylindrical metal band which connects a pair of outwardly projecting integral ears having holes for receiving a tangential screw and nut. The adjustable screw provides for accommodating variations in the diameter of the hose and also permits tightening the band to a predetermined compression in addition to permitting the removal and reuse of the hose clamp. Hose clamps may also be made in adjustable interconnecting sections, for example, as disclosed in U.S. Pat. No. 1,340,937.
In one hose clamp which is commonly used, a narrow tongue is punched from the band and is folded back to bridge the gap between the ears so that a clamping force is applied completely around the hose. The band is constructed of a relatively heavy gauge sheet metal, for example, 0.040 inch or greater, in order to avoid bending of the integral ears and to provide the narrow tongue with sufficient strength.
In view of the substantial number of hose clamps which are used, for example, in the appliance industry, there have been many efforts to reduce the cost of producing hose clamps so that they can be sold in volume at a low price. For example, the manufacturing cost has been reduced by eliminating the nut which receives the machine screw. Thus in one clamp design, the sheet metal forming the ear which receives the screw threads is extruded slightly to form the hole in the ear, and the extrusion is threaded to receive the screw.
It is also known to form the ear by double folding the end portion of the metal band and providing a threaded hole within the ear, for example, as disclosed in U.S. Pat. No. 1,187,430. The sheet metal which forms the ear may also be stamped and heat treated to form either a double sheet metal nut such as disclosed in U.S. Pat. No. 3,648,335 or a single sheet metal nut such as disclosed in U.S. Pat. No. 2,335,464 and U.S. Pat. No. 2,359,418. However, in each of these hose clamp designs, the metal which forms the combined ear and nut, must have substantial thickness and/or be of a steel which can be tempered hard to prevent stripping of the screw through the sheet metal nut.
It is apparent from the hose clamps referred to above that the substantial strength which is required in the ears in order to maintain the ears substantially perpendicular to the axis of the tangential screw and to prevent collapsing of the ears and/or stripping of the screws through the ears, has dictated that the clamp be formed from a sheet metal strip having substantial strength and resistance to bending. Thus the sheet metal is selected on a basis of strength required in the ears of the clamp rather than on a basis of the strength required in the part of the clamp which extends around the hose. As a result, the hose clamps are commonly produced from cold rolled carbon sheet metal having substantial thickness which also tends to prevent the clamp from conforming to an out-of-round condition and thus increases the possibility of a leak developing with a non-cylindrical hose.
It is further desirable for a hose clamp to apply a radial clamping force over a substantial area of the hose in a manner whereby the clamping force is not significantly released by either softening or "cold flowing" of the hose material as a result of the clamping pressure being applied over a substantial period of time. U.S. Pat. No. 3,765,066 discloses one form of hose clamp which was designed to maintain a continuous clamping pressure around the hose.